A digital versatile disc (DVD) player is composed of three logical units, as defined in the DVD specification. The first logical unit is a DVD player application that presents an interface to the user and relays user commands to the second logical unit. The second logical unit a DVD navigator that reads and interprets the information on the DVD and controls which segments of video and audio are processed based on the user commands. The third logical unit is a DVD presentation layer that decompresses data read from the DVD and presents the corresponding audio, video and subpicture streams, as applicable, to one or more renderers.
These logical units may be implemented in hardware and/or software. By way of example, in certain implementations, the DVD player is implanted via a graphical user interface (GUI) that is displayed to a user, and through which the user is able to selectively control playback, etc., of the DVD using a pointing selection input device, e.g., a mouse. This is usually a fairly straightforward task for system developers and allows for easy customization.
Implementing a DVD navigator, on the other hand, tends to be a more complex task. This is especially true for applications that seek to integrate DVD information into presentations and the like. Here, each developer entity would need to provide a mechanism for reading and interpreting their DVD, and interfacing with the decoder mechanism in the DVD presentation layer. Moreover, the decoder mechanism in the DVD presentation layer will likely be a product of a third party; making the task of authoring a DVD navigator even more difficult, the navigator must interface to many different decoder mechanisms.
Consequently, there is a need for a powerful yet simplified and consistent interface that player applications can use to control the DVD navigator program.